1. Field of the Invention
The present invention relates to a television receiver including a function to attach a detachable portable storage medium to, e.g., a digital camera and display a video signal recorded therein on a screen, and a control method thereof.
2. Description of the Related Art
As is well known, a portable memory card having a built-in semiconductor memory is detachable in a digital camera. Further, in the digital camera, an optical image of a photographed object is converted into an electrical video signal and stored in the memory card. In this case, the video signal stored in the memory card is based on a progressive mode.
Furthermore, there has been developed a television receiver which has a function to attach such a memory card and display a video signal recorded therein on a screen. This television receiver converts a video signal read from the memory card into a signal based on the interlaced mode of the NTSC (National Television System Committee) standard, and displays it on a CRT (cathode ray tube).
Moreover, in this television receiver, sequential scanning conversion processing can be applied to video signals converted into signals based on the interlaced mode in order to convert them to video signals based on the progressive mode, thereby enhancing the quality of displayed images.
Here, when a video signal read from the memory card is still picture video, sequential scanning conversion processing to combine video signals of adjacent fields after interlace conversion is applied, thereby displaying a still picture image with the grade of the original video recorded in the memory card.
On the other hand, when a video signal read from the memory card is a moving picture video, since sequential scanning conversion processing based on scanning line interpolation is applied to each field after interlace conversion, there occurs a problem that the grade of a video to be displayed is degraded.
This problem is visually confirmed by a user as an out-of-focus feeling that a contour becomes blurred in a vertical direction of a screen or a jagged feeling that a diagonal line is stepped. Additionally, this problem likewise occurs when displaying a moving picture video created by applying editing processing such as slides, thumbnails, zooming and others to a video signal recorded in the memory card.
Jpn. Pat. Appln. KOKAI Publication No. 2002-10219 discloses that sequential double-speed conversion or field double-speed conversion is carried out in such a manner that a high-quality video can be displayed with less flicker obstructions in accordance with a video signal format based on a television mode and a type of a display monitor when displaying video signals based on different television modes, but it does not have any description about solving the above-described problem.